Universal mechanical hand and holding fixture therefor



Aug. 12, 1958 J. M. HILL ETAL 2,846,906

UNIVERSAL MECHANICAL HAND AND HOLDING FIXTURE THEREFOR Filed NOV. 14, 1955 2 She ets-Sheet 1 INVENTORS u/mzr/z #141 CKOlS' Aug. 12, 1958 v J. M. HILL ET AL ,8

UNIVERSAL MECHANICAL HAND AND HOLDING FIXTURE THEREFOR 2 Sheets-Sheet 2 i d Nov. 14, 1955 IN V EN TORS United State Patent UNIVERSAL MECHANICAL HAND A'ND HOLDING FIXTURE THEREFOR James M. Hill and Edgar R. Nuckols, San Antonio, Tex., 'assignors to the United States of America as represented by the Secretary of the Air Force Application November 14, 1955, Serial No. 546,839

9 Claims. (Cl. 81'-17) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to us of any royalty thereon.

This invention relates to a universal mechanical hand and a holding fixture therefor, and more particularly to a device for holding irregularly shaped articles and articles of ditferent sizes upon which work is to be done.

A further object of the invention is the provision of a holding device which is rotatable about an axis so that an article placed therein and processed can be rotated to more accessible positions and at the same time leave both of the operators hands free.

A further object of this invention is the provision of a holding device which has the characteristics of an actual human hand in that it has a thumb or rear fingerlike member and a plurality of oppositely disposed fingers adapted to yieldably grip irregularly shaped work.

A further object of the invention is the provision of a resiliently yieldable holding device, one end of which is mounted for rotative adjustment on a table and operated by the foot of the operator.

A further object of the invention is the provision of a holding device having a series of holding fingers each of which exerts independent and individual resilient holding pressure upon the article which is being processed.

A further object of the invention is the provision of a holding device constructed so that irregularly shaped articles can be firmly and resiliently grasped and held with a substantially even distribution of holding pressure.

A further object of the invention is a device possessing all of the above noted characteristics and in addition is sturdy, easily and economically constructed and is not subject to damage nor frequently in need of repairs.

Further objects and advantages will become apparent as the description proceeds.

In the drawings, Fig. 1 is a side elevation showing the entire device with a portion of the pulley cable broken away;

Fig. 2 is a fragmentary side elevation, some parts being merely broken away, and other parts being broken away and shown in section;

Fig. 3 is a top plan view of Fig. 2;

Fig. 4 is an enlarged-scale cross-sectional view taken substantially on the line 4--4 of Fig. l; and looking in the direction of the arrows;

Fig. 5 is an enlarged-scale front view of the thumb or rear finger member, part of the finger covering being broken away, and shown in section.

Referring more in detail to the drawings, the device is mounted upon a table or any other suitable standard and comprises a block or housing member 12 provided with a pair of horizontally placed feet or flanges 14 which serve as anchoring flanges. The housing 12 is secured to the table or standard 10 by any suitable or desired means. In the present showing this is achieved by nut and bolt fastenings 16. The housing 12 is also provided with a cylindrical opening therethrough, and is slit vertically to form a pair of upstanding spring jaws 18 which form a clamping journal for a shaft member 20. The upstanding jaws are held at a predetermined, adjustable spaced distance by means of an adjusting bolt 22. A clamping screw 24 is engaged by a nut having a handle 26 to tighten and loosen the grip of the jaws 18 upon the member 20. The shaft member 20 constitutes a trunnion arm for a cradle member 28, which is radially ofiset therefrom. The cradle member 28 is formed with a vertically extending portion 30 which has a conico-frustum-shaped opening 32 communicating with and forming a continuation of an opening 34 in the supporting shaft member 20. A collar 29 secured on the end of the shaft 20and a spaced shoulder 31 secure the cradle against horizontal displacement. The open lower area of the cradle member 28 is closed if desired by means of a plate 36. The plate 36 is secured by any suitable means such as screws 38. The removal of the plate 36 allows access to the interior of the cradle member 28 from its under side and provides for adjustment and replacement of parts.

The cradle member 28 has an opening completely through it. The side walls of the opening are parallel and vertical. Each of the end walls protrudes inwardly to form an angular portion 28a flared outwardly'toward the top to make room for the movement of the thumb and finger elements later described, and an angular portion 28]) flared outwardly toward the bottomto form abutments 40 and 42. A pair of pivot pins 44 and 46 extend transversely through the cradle member 28 and are secured in its walls. The rear pin 44 has journaled thereon for pivotal movement a block 47 shown in detail in Fig. 5, and extending transversely across the interior of the cradle. A rear finger or thumb element 48 extends upwardly from the block 47 and is formed integral therewith or may be rigidly secured thereto. The block is formed as shown best in Figs. 1 and 2 with a forwardly extending actuating shoulder 49 at or near its lower edge. Each of a series of complemental clamping finger members 50 are individually pivoted in laterally spaced relation on the pivot pin 46. Three are shown, but the invention is not limited to any specific number. The lower portion of each finger member is provided, on the opposite side of the pivot 46, with a downwardly protruding lug portion 51, adapted to be engaged by the actuating shoulder member 49.

The thumb member is actuated to open position by positive means later described. When this occurs, the lugs 51 on the lower portion of the fingers are engaged by the shoulder 49 and are rocked upwardly thus positively opening the thumb and fingers.

The rear finger element 48 is curved as shown in Figs. 1 and 2, and is operable to be drawn to open position by the foot pedal 52. The foot pedal 52 is of any suitable construction and is here shown with a foot pad 54. It is pivotally connected to a bracket on a floor or any other desired support at a pivot point 56. It is to be understood that the actuating means for the device is not limited to a foot pedal but may be adapted for hand operation or any desired mechanical or push-button operation.

As shown, the foot pedal 52 is operably connected to and operates the finger portion 48 by the following means. A U-shaped outer end 60 of a link 58 has pivotal, universal connection to a rearwardly extending lug on the rear finger member 48 through a U-shaped link 64, a hinge bolt 62, and a pivot bolt 66. The opposite or inner end of the link 58 is secured to acable 68 which extends through the communicating recesses 32 and 34, and rides over a pulley 70. The pulley 70 is journaled on an arm 72 which projects rearwardly from the casing 12 and is protected 3 by a pulley shield 74. The cable 68 is connected to the operating pedal 52 by any suitable means such as link 76, turnbuckle 78 and pivot pin 81).

it will be seen that the opening of the mechanical hand-like device to release an object held thereby is done by positive means. When thefoot pedal is released, however, the thumb and fingers are biased toward a grasping or -a closed position by resilient means as follows:

The lower portion of the block 47 is provided with a downwardly extending portion which is provided with a series of slots 84 equal in number to the number of fingers 50. Each finger 50 is provided with a single downwardly extending portion provided with a slot 86. These slots are provided with facing concave or spherical bearing portions 94 which seat spherical ends of a series of thimble members 96. The thimble members 99 are provided with bores through each of which a rod 92 is inserted for relatively sliding movement. The thimbles form seats for a series of pairs of coaxial compression springs 88.

In assembling, the springs, rods, and thimble units are inserted upwardly into the lower opening 231) of the cradle mmber 28 and slipped into the slots 84 and 86, the spherical ends of the thimbles gt being received in the concave portions 94. The pairs of coaxial springs are thus held in partially compressed condition, their tension being in outward or opposite directions, thus biasing the upper ends of the fingers 48 and 5% of the mechanical hand toward each other to resiliently grasp and hold an article therebetween.

It will thus be seen that the inoperative position of the jaw or finger members 48 and 5% will be that shown in Fig. 1, while the clamping position of the jaws when an article such as indicated at 56a is positioned therebetween, is shown in 'Figure 2. It will also be seen that force exerted upon the .article to hold it between the fingers is resilient, and that each finger exerts its own independent individual force.

When it is desired to open the jaws for the release of an article the operating pedal 52 is pressed downwardly to pull back the rear finger 48, the conico-frustum-shaped openings 32 and 34 accommodating the arcuate movement of the link 58 and the pulley cable 68 within the trunnion shaft 20. During this movement of the rear finger member 48, the shoulder 49 engages the lugs 51 and rocks the finger members 53 outwardly. The jaws 48 and 50 are thus opened for the release or insertion of an article. The springs Sfi and 39 are brought under tension during this operation and as soon as the operating pedal 52 is released, the rear finger 4S and the front fingers 50 approach each other and grasp the article with a firm, even and resilient pressure. This resilient pressure is comparable to the grasp of a human hand, wherein each finger exerts its own individual resilient force. This effect is further augmented by the fact that the fingers I 48 and 50 are covered with a soft, non-abrasive, nonscratching material such as rubber, cloth, impregnated cloth, plastics or any other material deemed desirable. If rubber is vulcanized on metal, it has been found to possess advantageous frictional properties which aid in holding anarticle.

It will also be seen that the mounting of the trunnion member 20 of the cradle member 28 within the jaws 13 allows for a rotative change of position of the handlike elements through an arc, the center of which coincides with the axis of the shaft or trunnion member 2%. Thus the position of an article being processed can be changed as desired.

The operation of the handle 26 in an upward direction will loosen the clamp screw 24 to release the jaws and loosen the bite upon the trunnion member 20; whereupon the cradle member may be rotated to any desired position. The handle is then lowered and the jaws clamped tightly enough to again hold the cradle member firmly in the desired position.

Upon inspection of Fig. 3, it Will be seen that the finger 48 is not placed directly at the mid point of the block 47, but slightly offset to one side of the center one of the fingers 58. This provides a better stabilizing clamping relation between the cooperating finger members.

While the invention is shown and described in connection with one form for illustrative, rather than restrictive purposes, it is obvious that minor changes and modifications maybe made by those skilled in the art without departing from the scope and function of the invention as defined in the accompanying claims.

We claim:

1. In an adjustable article-holding device a cradle member provided with an integral hollow trunnion shank, a supporting bearing therefor comprising a pair of clampmembers for exerting clamping action on said trunnion shank, means for releasing or tightening said clamping members on said shank for allowing rotative movement of said cradle member, a thumb and a plurality of oppositely disposed fingers pivotally mounted in said cradle member, resilient means for biasing said thumb and said fingers toward each other into an article-holding position, a pulley, a cable secured to said thumb and passing through the hollow in said trunnion shank, over said pulley, and connected to foot pedal means to draw said thumb to open position, a lug on each of said fingers, an actuating shoulder on said thumb for engaging the lugs on said fingers for moving said fingers into open position when said thumb is drawn to said open position.

2. A universal hand and operating mechanism therefor comprising a cradle member, supporting means for said cradle, means for imparting arcuate motion to said cradle member about a predetermined axis, a block pivotally mounted in said cradle member, a grasping thumb and a lug on said block positioned on opposite sides of the pivot, a plurality of opposed finger members pivotally mounted in said cradle member, resilient means for biasing each finger member to closed position independently, each of said resilient means at the same time biasing said thumb member also toward closed position, means for moving said thumb member to open position, said lug actuating said finger members in unison to open position when said thumb member is actuated to open position.

3. A universal mechanical hand and means for positioning and operating said hand comprising a support, a cradle mounted on said support for arcuate movement about a horizontal axis, a curved thumb mounted for pivotal movement in said cradle, means for actuating said thumb to open position, a plurality of curved fingers pivotally mounted in said cradle and positioned in opposed gripping relation to said thumb, a block formed integrally on the lower portion of said thumb and provided with an actuating shoulder, a lug formed on the lower portion of each of said fingers, said lugs being engageable by said shoulder to move said fingers to open position when said thumb is moved to open position, a spring-seating means on each finger, a plurality of springseating means on said block, a spring mounted between said block and each of said fingers, said springs operating to bias individually said thumb and said fingers toward closed position, whereby independent and individual pressure is exerted by each of said fingers on an article placed therebetween.

4. A mechanical universal hand comprising a cradle, two parallel pivot pins extending through said cradle, a block pivoted on one :of said pivot pins and carrying an integral thumb, means for actuating said thumb to open position, an actuating abutment shoulder on said block, an undercut portion on said block pro-vided with a plurality of open slots, a plurality of fingers pivoted to the other of said pivot pins in opposing relation to said thumb, each finger provided with a protruding lug engageable by said actuating abutment shoulder to operate the fingers to open position when said thumb is operated to open position, each finger having a slot in its lower portion, resilient means between the lower ends of said thumb and fingers for biasing said thumb and fingers to grasping position, said resilient means comprising a set of rods inserta-ble in the slots in said block and said fingers, a thimble seated in a thimble seat formed in each of said slots, each thimble having an opening therethrough for slidably receiving an end of one of said rods, springs surrounding said rods and seating on said thimbles, said springs providing individual separating pressure on the lower ends of each of said fingers and concerted pressure on said thumb to bias said thumb and fingers toward closed or grasping position.

5. A universal hand and a holding fixture therefor comprising a cradle member, fingers for holding an article to be processed mounted in said cradle member, positive means for opening said fingers and resilient means operating individually on each finger for biasing said fingers to closed position, an arm and shank on said cradle, a substantially conico-frustum-shaped aperture through said arm and shank, releasable jaw means for holding said shank in selected rotary position, said positive operating means comprising a universal joint attached to one'of said fingers, a cable attached to said universal joint and extending through said aperture and means for operating said cable to move said fingers to open position.

6. A universal mechanical hand comprising a thumb and an oppositely disposed set of fingers, a cradle for mounting said hand, said thumb and fingers each being pivotally mounted between their ends to said cradle, complementary grasping surfaces on said thumb and said fingers, interacting lugs on said thumb and fingers positioned on ends opposite their grasping surfaces, means for moving said thumb to open position, said fingers being opened at the same time by the interaction of said lugs, said means comprising a foot pedal, and a pulley and cable, said cable being connected to said thumb through a universal joint, said cradle being provided with an orifice of conico-frustum formation to allow arcuate movement of said thumb.

7. In a universal mechanical hand and mounting therefor, a journal shaft, means for mounting said shaft for rotation about a horizontal axis, a cradle integral with said shaft and radially ofiset therefrom, said shaft being provided with a bore throughout its length of substantially conico-frustum formation, elements of a universal hand mounted in said cradle, said cradle being provided with an opening therethrough, cable means for moving the elements of said hand out of gripping position, said cable extending through the bore in said shaft and being connected to one element of said hand through a universal joint, resilient means mounted in said cradle for biasing the elements of said hand to closed position, and abutrnents positioned on said cradle and extending into said openings to limit the closing movement of the elements of said hand.

8. In a mechanical hand, a support for said hand, a thumb and finger members pivoted between their ends to said support, grasping portions on said thumb and finger members, a block on said thumb member opposite the pivot, said block being provided with communicating slots and spherical recesses, blocks on said finger members opposite said pivots, spherical recesses in said lastnamed blocks facing oppositely to said first-named recesses, said last-named recesses communicating with slots in said last-named blocks, thimbles fitted into each recess, each thimble being provided with an axial bore, rods extending through the axial bores of opposite pairs of thimbles, spring means interposed between said thimbles, means for operating said thumb to open position, the block on said thumb operating on the blocks on said fingers to move said fingers in unison to open position, and said spring means biasing each finger independently to closed position.

9. In a mechanical hand, a support for said hand, a. thumb and finger members pivoted between their ends to said support, grasping portions on said thumb and finger members, a block on said thumb member opposite the pivot from said grasping portions, said block being provided with spring seats, blocks on said finger members opposite said pivots from said grasping portions, spring seats on said blocks, spring means interposed between the block on said thumb member and the blocks on said finger members, means for operating said thumb to open position, said block on said thumb at the same time operating on the blocks on said fingers to move them to open position in unison, and said springs operating to bias said thumb and finger members to closed position independently.

References Cited in the file of this patent UNITED STATES PATENTS 1,305,169 Rohrmann May 27, 1919 FOREIGN PATENTS 8,295 Norway May 7, 1900 

